1. Field
One embodiment of the invention relates to a moving picture decoding apparatus, a moving picture decoding method, and a storage medium storing a moving picture decoding program.
2. Description of the Related Art
A moving picture decoding apparatus decodes coded and compressed moving picture data. When decoding moving picture data, the moving picture decoding apparatus commonly uses a technique to make motion appear smooth by predicting a motion between consecutive frames, generating an interpolation image, and interposing the generated interpolation image between the frames.
At the time of generating the interpolation image, in general, a motion-vector which denotes a motion of an object moving in a picture is detected. Then, based on the motion-vector, the motion in the picture between the frames is predicted and the interpolation image is generated.
For example, Jpn. Pat. KOKAI Publication No. 2006-279917 describes a technique of extracting information required to estimate a motion-vector from an input stream and performing a frame interpolation process.
The interpolation image is generated to smooth motion of a moving picture. However, there may be a case in which the generation of the interpolation image is not necessary or interposing the interpolation image even causes deterioration in quality of the moving picture.
For example, interposing an interpolation image between motionless frames produces no visual effect and wastes the amount of calculations. In addition, when continuity is not maintained between frames, e.g., a case in which an image is suddenly switched in the moving picture, prediction of a motion may bring inaccurate result and the interpolation image may be defective. Even in the case where continuity of motion is maintained, when the picture has plural major motions, prediction may fail at a boundary between the motions and false outlines may be created. Accordingly, it may appear that noise is generated. In such cases, generation of the interpolation image is not effective and only causes increase in the amount of calculations.